In a substrate processing system, an atmospheric transfer chamber is provided between a storage container for receiving a wafer and a substrate processing chamber maintained at a preset vacuum state so as to connect the storage container with the substrate processing chamber. Further, a wafer is held by an arm or the like and transferred between the substrate processing chamber and the storage container. An unprocessed wafer in the storage container is transferred to the substrate processing chamber and a plasma process is performed thereon, and then the wafer as a processed wafer is accommodated again in the storage container. In the substrate processing chamber, for example, a reactive ion etching (RIE) process may be performed as a preset plasma process. The storage container is called “FOUP,” “carrier” or the like.
The processed wafer re-accommodated in the FOUP can be contaminated due to atmosphere within the FOUP (secondary contamination), resulting in a decrease in production yield of the processed wafer. According to a mechanism of the secondary contamination, an atmosphere gas (e.g., halogen-based residual gas), a halogen-based reaction product and the like (hereinafter, simply referred to as “foreign materials”) within the substrate processing chamber are adhered to a surface of the RIE-processed wafer and these foreign materials are introduced into the FOUP together with the wafer. Here, even if a small amount of the foreign materials is adhered to each processed wafer, a plurality of wafers is loaded into the FOUP which is a closed and narrow space, and, thus, the inside of the FOUP can be contaminated by the foreign materials. Therefore, an unprocessed wafer or a processed wafer can be secondarily contaminated.
In Patent Document 1 regarding a technique of cleaning the inside of the FOUP, a gas supply pipe is provided above an opening in a so-called FIMS (Front-Opening Interface Mechanical Standard) and a cleaning gas is blown from the pipe toward an upper surface of a wafer accommodated in the FOUP in order to remove contaminants from the wafer in the FOUP.
It is disclosed in Patent Document 2 that there is installed an air substitution mechanism which substitutes a clean gas for a gas within a FOUP in order to maintain the inside of the FOUP accommodating wafers at a desired gas atmosphere.
Patent Document 1: Japanese Patent Laid-open Publication No. 2006-128153
Patent Document 2: Japanese Patent Laid-open Publication No. 2006-351619